The mechanisms used by bacteria and fungi to oxidize carcinogenic polycyclic hydrocarbons will be investigated at the chemical and enzymatic levels. A Beijerinckia sp. and a mutant strain, Beijerinckia sp. B836, that oxidizes polycyclic hydrocarbons to cis-dihydrodiols will be used to investigate the metabolism of benzo(a)pyrene, benzo(a)anthracene and 3-methylcholanthrene. Similar experiments will be conducted with fungus Cunninghamella elegans. Products will be isolated by high-pressure liquid chromatography and identified from the information provided by infrared, visible and ultraviolet spectrophotometry, mass and proton magnetic resonance spectrometry. The enzymes responsible for the oxidation of benzo(a)pyrene in C. elegans will be characterized in termms of cellular location and physical Properties. It is anticipated that cytochrome P-450, reductase, epoxide hydratase and glutathione S-transferase activity will be detected in this eucaryotic microorganism. The results will establish the different metabolic pathways used by bacteria and fungi for the metabolism of polycyclic hydrocarbons. Such reactions will almost certainly occur in the environment. Also, polycyclic hydrocarbon derivatives should be obtained that will be useful in studies on the initiation of chemical carcinogenesis in mammals. In addition to providing potential microbial model systems for drug metabolism and chemical carcinogenesis the proposed research should establish the fundamental biochemical differences between procaryotic and eucaryotic organisms in terms of polycyclic hydrocarbon oxidation.